In this study, AIDS patients with gastrointestinal CMV disease will be randomized to one of three doses of oral ganciclovir. Pharmokinetics with and without glutamic acid (increases bioavailability), highest acheivable plasma concentrations, comparison of plasma concentration of IV to oral ganciclovir are primary objectives. Tolerance, time to relapse, and efficacy of oral ganciclovir will be also be determined.